Photodegradation chemistry of the insecticide phosmet in lipid models and in the presence of wool wax, employing a 15N-labeled compound

The organophosphorus insecticide phosmet is commonly used for plant protection as well as against pests on animals. Phosmet features numerous degradation pathways induced by UV irradiation. In this study, we focused on the reaction possibilities of phosmet in the presence of lipophilic substances with olefinic structure elements, as they are frequently found in animal fur lipids, especially in wool wax. In the first step, simple models were employed to characterize the structural types of formed photoaddition products. On irradiation in the presence of cyclohexene, three photoaddition products were identified, a (4pi + 2pi) cycloaddition product of phosmet and cyclohexene and two diastereoisomer carbinols. Likewise, in more sophisticated models employing fatty acid methyl esters for irradiation experiments, phosmet was readily photodegraded. In the presence of methyl oleate, also 1:1 photoaddition products could easily be identified by means of liquid chromatography-mass spectrometry, using a stable isotope-labeled phosmet (15N-phosmet, 50 at. %) for the photolysis experiments. To converge from models to the more complex natural environment of animal skin lipids, irradiation experiments of phosmet in the presence of wool wax were performed. After 24 h of irradiation, only a remnant of 1.4% of the initial phosmet was detectable. Phosmet-oxon was detected in concentrations up to 27.3 mol %.     

Photolysis experiments on phosmet, an organophosphorus insecticide

The organophosphorus insecticide phosmet is used in plant protection as well as against parasites on animals. Phosmet showed numerous photoinduced reaction pathways, which first were studied in the presence of model environments for animal fur lipids (e.g., wool wax). The model solvents for saturated and unsaturated lipids were cyclohexane and cyclohexene, whereas methanol and 2-propanol were used as models for primary and secondary alcohol moieties of lipids. The measured degradation rates over an irradiation period of 7 h in all solvents used were very similar (49-55%). The obtained photoproducts generally included phthalimide, N-hydroxymethylphthalimide, and N-methoxymethylphthalimide. Furthermore, depending on the solvent used, additional degradation products were detectable as N-isopropoxy- and N-methylphthalimide in the presence of 2-propanol and cyclohexene, respectively. However, in the presence of cyclohexene, despite the similar turnover, distinctly lower concentrations of photoproducts were found, indicating further still unknown degradation pathways. Irradiations in methanol with increasing percentages of water led to higher degradation rates; however, the products were found to be the same. Irradiation experiments with pure phosmet on silica TLC plates and glass surfaces resulted in degradation rates of 19 and 32%, respectively, after 6 h. The results obtained clearly demonstrate for the first time that the photoinduced degradation of phosmet is strongly dependent on the chemical environment, affecting less the turnover than the photoproducts formed. The results additionally demonstrate the need to investigate the degradation behavior of phosmet on wool and in the presence of wool wax.     

Evaluation of chemical and photochemical oxidation processes for degradation of phosmet on lowbush blueberries (Vaccinium angustifolium)

Chemical and photochemical oxidation processes were evaluated for their ability to degrade residual phosmet on lowbush blueberries and for their role in the conversion of phosmet to phosmet oxon--a toxic metabolite of phosmet. Chemical processes included 1 ppm of aqueous ozone, 1% hydrogen peroxide, 100 ppm of chlorine, and UV, whereas photochemical processes included hydrogen peroxide/UV, chlorine/UV, and ozone/hydrogen peroxide/UV. Phosmet applied as Imidan 2.5EC under laboratory conditions resulted in a mean residual concentration of 44.4 ppm, which was significantly degraded (p < 0.05) by ozone and chlorine, yielding reductions of 57.7 and 46%, respectively. Interaction between phosmet (Imidan 2.5EC) and any chemical or photochemical treatment did not result in conversion to phosmet oxon. Residual analysis of commercially grown blueberries revealed mean phosmet (Imidan 70W) levels of 10.65 ppm and phosmet oxon levels of 12.49 ppm. Treatment of commercial blueberries resulted in significant reductions in phosmet regardless of treatment type; however, only UV, hydrogen peroxide/UV, and ozone treatments degraded phosmet (Imidan 70W) to less toxic metabolites and reduced phosmet oxon levels. Treatment-induced conversion of phosmet to phosmet oxon was noticeably influenced by variations between phosmet formulations. Acceleration of photochemical degradation by UV was not observed. Selective oxidation by ozone represents a significant postharvest process for degrading residual phosmet on lowbush blueberries.     

Nitrogen isotope composition of organically and conventionally grown crops

Authentic samples of commercially produced organic and conventionally grown tomatoes, lettuces, and carrots were collected and analyzed for their delta15N composition in order to assemble datasets to establish if there are any systematic differences in nitrogen isotope composition due to the method of production. The tomato and lettuce datasets suggest that the different types of fertilizer commonly used in organic and conventional systems result in differences in the nitrogen isotope composition of these crops. A mean delta15N value of 8.1 per thousand was found for the organically grown tomatoes compared with a mean value of -0.1 per thousand for those grown conventionally. The organically grown lettuces had a mean value of 7.6 per thousand compared with a mean value of 2.9 per thousand for the conventionally grown lettuces. The mean value for organic carrots was not significantly different from the mean value for those grown conventionally. Overlap between the delta15N values of the organic and conventional datasets (for both tomatoes and lettuces) means that it is necessary to employ a statistical methodology to try and classify a randomly analyzed "off the shelf" sample as organic/conventional, and such an approach is demonstrated. Overall, the study suggests that nitrogen isotope analysis could be used to provide useful "intelligence" to help detect the substitution of certain organic crop types with their conventional counterparts. However, delta15N analysis of a "test sample" will not provide unequivocal evidence as to whether synthetic fertilizers have been used on the crop but could, for example, in a situation when there is suspicion that mislabeling of conventionally grown crops as "organic" is occurring, be used to provide supporting evidence.     

Carbon and hydrogen stable isotope ratios of carotenoids and beta-carotene-based dietary supplements

Considering the increasing nutritional and commercial importance of carotenoids, there is an interest in developing a reliable method for authenticity assessment of these compounds. Applying isotope ratio mass spectrometry using elemental analysis in the "combustion" (C) and "pyrolysis" (P) modes (EA-C/P-IRMS), the delta (13)C V-PDB and delta (2)H V-SMOW values of selected carotenoids and alpha/beta-carotene-based commercial dietary supplements were determined in comparison to those of synthetic and "natural" references. The delta (13)C V-PDB and delta (2)H V-SMOW values of synthetic beta-carotene samples ( n = 4), ranging from -25.3 per thousand to -26.4 per thousand and from -144 per thousand to -155 per thousand, respectively, differed clearly from the data determined for carotenoids from various natural sources, including C 3 plant material ( n = 9; delta (13)C V-PDB ranging from -28.5 per thousand to -32.8 per thousand and delta (2)H V-SMOW from -180 per thousand to -275 per thousand) and microalgae Dunaliella salina ( n = 1; delta (13)C V-PDB value of -15.6 per thousand and delta (2)H V-SMOW value of -191 per thousand). From five commercial dietary supplements under study, two revealed delta (13)C V-PDB and delta (2)H V-SMOW values in areas as found for synthetic references, and the other three had values near those of biotechnological beta-carotene produced by D. salina. The delta (13)C V-PDB and delta (2)H V-SMOW values recorded for natural lycopene ( n = 4) and lutein ( n = 5) ranged from -31.1 per thousand to -31.8 per thousand and from -180 to -201 per thousand, as well as from -28.8 per thousand to -32.2 per thousand and from -186 per thousand to -245 per thousand, respectively. Synthetic canthaxanthin ( n = 3) exhibited delta (13)C V-PDB and delta (2)H V-SMOW values ranging from -25.0 per thousand to -28.6 per thousand and from -133 per thousand to -153 per thousand, respectively. The EA-C/P-IRMS application of this study showed that the natural stable isotopic composition of carotenoids is a powerful tool for determining their origin.     

On-line gas chromatography combustion/pyrolysis isotope ratio mass spectrometry (HRGC-C/P-IRMS) of pineapple (Ananas comosus L. Merr.) volatiles

By use of extracts prepared by liquid-liquid separation of the volatiles from self-prepared juices of pineapple fruits (Ananas comosus) (n = 14) as well as commercial pineapple recovery aromas/water phases (n = 3), on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and the pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta(13)C(VPDB) and delta(2)H(VSMOW) values of selected pineapple flavor constituents. In addition to methyl 2-methylbutanoate 1, ethyl 2-methylbutanoate 2, methyl hexanoate 3, ethyl hexanoate 4, and 2,5-dimethyl-4-methoxy-3[2H]-furanone 5, each originating from the fruit, the delta(13)C(VPDB) and delta(2)H(VSMOW) data of commercial synthetic 1-5 and "natural" (biotechnologically derived) 1-4 were determined. With delta(13)C(VPDB) data of pineapple volatiles 1-4 varying from -12.8 to -24.4 per thousand, the range expected for CAM metabolism was observed. Compound 5 showed higher depletion from -20.9 to -28.6 per thousand. A similar situation was given for the delta(2)H(VSMOW) values of 3-5 from pineapple ranging from -118 to -191 per thousand, whereas 1 and 2 showed higher depleted values from -184 to -263 per thousand. In nearly all cases, analytical differentiation of 1-5 from pineapple and natural as well as synthetic origin was possible. In general, natural and synthetic 1-5 exhibited delta(13)C(VPDB) data ranging from -11.8 to -32.2 per thousand and -22.7 to -35.9 per thousand, respectively. Their delta(2)H(VSMOW) data were in the range from -242 to -323 per thousand and -49 to -163 per thousand, respectively.     

碘甲磺隆钠盐在水溶液中的光解研究

为了解碘甲磺隆钠盐在水溶液中的光降解特性,评价其环境安全性,以太阳光和高压汞灯为光源,进行光解试验,研究了碘甲磺隆钠盐在不同水溶液中的光解行为及水体pH值对其光解的影响。结果表明,碘甲磺隆钠盐在所有试验水体中的降解均符合一级动力学方程,不同水体中碘甲磺隆钠盐的半衰期分别为14.29～21.26h（太阳光）与2.29～3.76min（高压汞灯）,两种光源下碘甲磺隆钠盐在各自然水体中的降解速率依次为井水〉河水〉池塘水〉稻田水。不同pH值水体中的光解实验表明,碘甲磺隆钠盐在酸性介质中的光解比在碱性介质中快,顺序为pH5〉pH7〉pH9〉pH11。     

Determination of the 2H/1H and 15N/14N ratios of Alkylpyrazines from coffee beans (Coffea arabica L. and Coffea canephoravar. robusta) by isotope ratio mass spectrometry

The delta15N(AIR) and delta2H(VSMOW) data for several alkylpyrazines formed during the roasting process of coffee are reported. Samples of commercially available roasted (n = 9) as well as self-roasted (n = 8) coffee beans (Coffea arabica L. and Coffea canephora var. robusta) of different origins were investigated. By use of extracts prepared by simultaneous distillation extraction (SDE) and subsequently fractionated by liquid chromatography on silica gel, on-line capillary gas chromatography-isotope ratio mass spectrometry was employed in the combustion (C) and pyrolysis (P) modes (HRGC-C/P-IRMS) to determine the delta15N(AIR) and delta2H(VSMOW) values, respectively. In addition to the constituents of coffee beans, data for commercial synthetic alkylpyrazines and substances declared to be "natural" were determined. The delta15N(AIR) data for coffee alkylpyrazines under study-2-ethyl-5-methylpyrazine (1) and 2-ethyl-6-methylpyrazine (2) (measured as sum 1/2), 2-ethyl-3-methylpyrazine (3), 2-methylpyrazine (4), 2,5-dimethylpyrazine (5) and 2,6-dimethylpyrazine (6) (measured as sum 5/6), and 2,3-dimethylpyrazine (7), as well as 2,3,5-trimethylpyrazine (8)-varied in the range from +8.3 to -10.2 per thousand, thus revealing their biogeneration from amino acids (delta15N(AIR) ranging from +8 per thousand to -10 per thousand). The delta2H(VSMOW) values were determined in the range from -5 per thousand to -127 per thousand. Owing to the analytical differentiation observed between coffee alkylpyrazines and synthetic/"natural" samples of 3, 4, and 7, authenticity assessment of coffee-flavored products seems to be promising, provided that extended data will be available in the future. In the literature, there were no IRMS data available for the alkylpyrazines (1-8) under study.     

The feasibility of using delta15N and delta13C values for discriminating between conventionally and organically fertilized pepper (Capsicum annuum L.)

A greenhouse experiment was conducted to determine the feasibility of using leaf and fruit delta15N and delta13C values to discriminate between conventionally and organically fertilized peppers, when conventional management involves the application of organic amendment for soil preparation. All of the treatments involved adding horse manure to the soil before applying different rates of synthetic N fertilizers: 0 (T1 and T2), 150 (T3), and 300 kg ha(-1) (T4). The difference between T1 and T2 was that no synthetic fertilizer had been applied to plot T1 during the 5 years prior to the experiment. Significant differences were found in the delta15N values of leaves and fruit from the plants grown under organic or mixed fertilization. The results indicate the possibility of using 15N natural abundance as an indicator of fertilization management. On the other hand, delta13C values did not contribute any additional information for discriminating between the organically and the synthetically and organically fertilized peppers.     

Application of multielement stable isotope ratio analysis to the characterization of French, italian, and spanish cheeses

The stable isotope ratios (delta13C, delta15N, and delta34S of casein and delta13C and delta18O of glycerol) measured by IRMS of French, Italian, and Spanish cheeses are presented and discussed. Variability factors such as animal-feeding regimen, geographical origin, and climatic and seasonal conditions were studied to check the possibilities of cheese characterization offered by each isotopic parameter. Delta13C values of both casein and glycerol appeared to be strongly correlated to the amount of maize in the animal diet. Delta15N and delta34S of casein proved to be mostly influenced by the geoclimatic conditions of the area (aridity, closeness to the sea, altitude). Delta18O of glycerol was more dependent on the geographical origin of the cheeses and on climatic/seasonal parameters. By applying a multivariate stepwise canonical discriminant analysis, good discrimination possibilities for the different European cheeses were obtained, confirmed by the classification analysis, when >90% of the samples were correctly reclassified.     

Detection of sugar syrups in apple juice by delta(2)H per thousand and delta(13)C per thousand analysis of hexamethylenetetramine prepared from fructose

An improved procedure for determining (13)C and (2)H isotope ratios, using gas chromatography-isotope ratio mass spectrometry (GC-IRMS), has been developed for identifying the addition of low cost commercial sugar syrups to apple juices and related products. Isotopic techniques are commonly used to identify the addition of low cost sugars to fruit juices and are difficult to circumvent as it is not economically viable to change the isotopic ratios of the sugars. The procedure utilizes the derivative hexamethylenetetramine, which is produced through chemical transformation of a sugar degradation product and provides position-specific (13)C and (2)H ratios that relate to the parent sugar molecule. The new procedure has advantages over methods using nitro-sugar derivatives in terms of analysis time and sensitivity. The differences between the delta(2)H per thousand and delta(13)C per thousand values of the 100 authentic apple juices and beet and cane commercial sugar syrups permit their addition to be reliably detected.     

Nitrogen metabolism components as a tool to discriminate between organic and conventional citrus fruits

The aim of this work was to develop a method for authenticity control of organically grown orange fruits. Due to the different kinds of nitrogen fertilization of the soil in organically and conventionally managed farms, the study tried to verify the possibility to differentiate Navelina and Tarocco orange fruits obtained by these production systems through the detection of markers linked to nitrogen metabolism. In addition to the classic quality parameters, total nitrogen (N) and synephrine contents in juice and (15)N/(14)N isotope ratio (expressed as delta(15)N per thousand) in proteins of pulp and amino acids of juice were determined. The results obtained indicated that total N and synephrine contents were significantly higher in conventional fruits, whereas the delta(15)N per thousand values were higher in the organic ones. The new markers identified in this research by linear discriminant analysis of the data may constitute a useful tool to differentiate organic citrus fruits or juices from conventional ones.     

Flavor authenticity studies by (2)h/(1)h ratio determination using on-line gas chromatography pyrolysis isotope ratio mass spectrometry

Based on (2)H/(1)H ratio measurements of commercial synthetic and "natural" references, the recently developed on-line gas chromatography pyrolysis isotope ratio mass spectrometry (HRGC-P-IRMS) technique was used to determine the delta(2)H(SMOW) values of the flavor compounds decanal, linalool, and linalyl acetate, as well as those of E-2-hexenal and E-2-hexenol in foods and essential oils. In preceding model studies, the influence of sample preparation steps (simultaneous distillation extraction, SDE; solvent extraction, SE; liquid liquid extraction, LLE) on the delta(2)H values was found to be negligible. For decanal, the typical (2)H abundance, with higher content of (2)H for synthetic material (delta(2)H(SMOW) from -90 to -156 per thousand) and lower (2)H content for natural references (delta(2)H(SMOW) from -138 to -262 per thousand) was observed. Although the delta(2)H data recorded for linalool did not allow one to distinguish between synthetic (delta(2)H(SMOW) from -207 to -301 per thousand) and natural (delta(2)H(SMOW) from -234 to -333 per thousand) materials, the situation was somewhat more encouraging for linalyl acetate; delta(2)H(SMOW) values from -199 to -239 per thousand and from -213 to -333 per thousand were found for synthetic and natural samples, respectively. E-2-Hexenal and E-2-hexenol showed clear-cut origin-dependent differences in their (2)H/(1)H ratios; that is, delta(2)H(SMOW) values from -14 to -109 per thousand and from -263 to -415 per thousand as well as from -41 to -131 per thousand and from -238 to -348 per thousand were recorded for products from synthetic and natural origins, respectively.     

Novel fatty acid esters of p-coumaryl alcohol in epicuticular wax of apple fruit

Hexane extracts of epicuticular wax from cv. Gala apples were noted to have an unusual, broad absorbance maximum at approximately 258 nm, which led us to isolate and identify the primary UV-absorbing compounds. Column and thin-layer chromatography yielded a fraction that gave a series of paired, 260-nm-absorbing peaks on C(18) HPLC. These were shown to be a family of phenolic fatty acid esters, for which retention times increased with increasing fatty acid chain length, and paired peaks were esters of two related phenolics with the same fatty acid moiety. Alkaline hydrolysis of the esters released two water-soluble phenolics separable by C(18) HPLC. Electrospray ionization mass spectrometry gave a molecular mass of 150 for both, and (1)H NMR plus UV absorbance spectra identified them as E and Z isomers of p-coumaryl alcohol. Alkaline cleavage of the fatty acid esters in the presence of methanol or ethanol resulted in partial derivatization of E-p-coumaryl alcohol to the corresponding gamma-O-methyl or O-ethyl ether. Gradient HMQC NMR of the HPLC-purified stearate ester of E-p-coumaryl alcohol indicated that fatty acid esterification occurs at the gamma-OH rather than at the 4-OH on the phenyl ring. This is the first report of fatty acid esters of monolignols as a natural plant product.     

Natural abundance of 15N in nitrate,ureides, and amino acids from plant tissues

The natural ¹⁵N abundances (δ¹⁵N values) were measured for nitrate and free and bound amino acids from the leaves of field-grown spinach (Spinacia oleracea L.) and komatsuna (Brassica campestris L.), as well as ureides and free and bound amino acids in the leaves and roots of hydroponically grown soybean (Glycine max L.) totally depending on dinitrogen. Nitrate from the spinach and komatsuna leaves and ureides from leaves and roots of soybean showed higher δ¹⁵N values than the total tissue N and N in free or bound amino acid fractions. The δ¹⁵N values of individual free and bound amino acids, determined by GC/C/MS using their acetylpropyl derivatives, were similar in leaf tissues except for proline but varied in soybean root tissues. The order of ¹⁵N enrichment was similar in the four samples: aspartic acid > glutamic acid > threonine, proline, valine > glycine + alanine +serine, γ-amino butyric acid, and phenylalanine.     

Examining the Microbial Degradation of Naphthenic Acids Using Stable Isotope Analysis of Carbon and Nitrogen

Naphthenic acids (NAs) are a complex group of naturally occurring oil sands constituents that constitute a significant portion of the dissolved organic carbon (DOC) pool available for microbial degradation in the process-related waste water associated with oil sands mine sites. One approach to understanding the biological fate of oil sands process-derived carbon and nitrogen in aquatic reclamation of the mine sites involves the use of stable isotope analyses. However, for stable isotope analyses to be useful in such field-based assessments, there is a need to determine how microbial degradation of a complex mixture of NAs might change the stable isotope values (δ ¹³C, δ ¹⁵N). In batch cultures and semi-continuous laboratory microcosms, utilization of a commercial mixture of NAs by oil sands-derived microbial cultures resulted in microbial biomass that was similar or slightly ¹³C enriched (1.4‰ to 3.0‰) relative to the DOC source, depending on the length of incubation. Utilization of a NA-containing extract of oil sands processed water resulted in greater ¹³C enrichment of microbial biomass (8.5‰) relative to the DOC source. Overall, the δ ¹³C of the DOC comprised of complex mixtures of NAs showed minimal change (?0.5‰ to ?0.1‰) during the incubation period whereas the δ ¹³C of the dissolved inorganic carbon (DIC) was more variable (?5.0‰ to +5.4‰). In tests where the concentration of available nitrogen was increased, the final biomass values were ¹⁵N enriched (3.8‰ to 8.4‰) relative to the initial biomass. The isotope trends established in this study should enhance our ability to interpret field-based data from sites with hydrocarbon contamination, particularly in terms of carbon source utilization and ¹⁵N enrichment.     

Effects of postharvest preparation on organophosphate insecticide residues in apples

Apples were sampled directly from orchard trees at 96, 45, and 21 days postapplication with one of three organophosphate insecticides (azinphos methyl, phosalone, or phosmet, respectively). Individual apples were prepared for analysis following one of three postharvest preparations: no preparation, rinsed with deionized water for 10-15 s, or rinsed and peeled. Azinphos methyl, phosalone, and phosmet concentrations ranged from below the level of detection to 5.26 ng/g, 94.7 to 5720 ng/g, and 0.011 to 663 ng/g in the apples that received no postharvest preparation, respectively. Although rinsed apples had lower maximum concentrations than observed in apples with no preparation, levels were not significantly lower. Concentrations of all three OP insecticides in apples that were rinsed followed by peeling, however, were much lower (below detection limits to 0.733 ng/g, azinphos methyl; 0.322-219 ng/g, phosalone; and below detection limits to 44.0 ng/g, phosmet) than observed in apples that had been rinsed alone. Rinsing and peeling of apples resulted in a 74.5-97.9% reduction in OP residues, while rinsing alone lowered mean concentrations by 13.5-28.7% relative to apples that received no postharvest preparation.     

Determination of the wax ester content in olive oils. Improvement in the method proposed by EEC regulation 183/93

A simpler and faster procedure than the official one described in document IV of European Economic Community Regulation 183/93 is proposed. The wax ester fraction is isolated from triglycerides using a commercially available silica gel column and carbon tetrachloride as eluent. The recovered wax ester fraction, with the addition of a suitable internal standard solution, is analyzed by gas chromatography. A column with a 65% phenyl methyl silicone stationary phase allows a satisfying separation of wax ester fraction in comparison with both a steryl ester and a light fraction eluted before the internal standard. Furthermore, also the single components of the wax ester fraction are suitably separated.     

Flavor authentication studies of alpha-ionone, beta-ionone, and alpha-ionol from various sources

In addition to the already available information on the authenticity of alpha- (1) and beta-ionone (2) from plant tissues, there is an interest in the stable isotope data of 1 and 2 available by synthesis from citral and acetone, as European Union regulations, in contrast to the United States and other countries, do not allow a product to be declared as 'natural' that has been chemically synthesized (e.g., by using a natural catalyst) from natural educts. Analyses performed by on-line capillary gas chromatography-isotope ratio mass spectrometry in the combustion and pyrolysis modes (HRGC-C/P-IRMS) as well as by elemental analyzers (EA-C/P-IRMS) measuring delta(13)C(V)-PDB and delta(2)H(V)-SMOW values provide for the first time isotope data of such 'natural' 1 and 2 as well as of synthetic and 'ex plant' alpha-ionol (3). The isotope data recorded for synthesized 1 and 2 reflected the influence of the origin of the used citral, whereas that of acetone was less remarkable. For instance, 'natural' 1 ex citral from lemongrass showed, as expected for a C4 plant, an enriched delta(13)C(V)-PDB value of -18.5 per thousand. In addition, the use of synthetic citral resulted in an enriched delta(2)H(V)-SMOW value of -43 per thousand, whereas with citral ex Litsea cubeba and ex lemongrass values of -242 and -232 per thousand, respectively, were recorded. IRMS analyses of 'natural' 2 revealed delta(13)C(V)-PDB and delta(2)H(V)-SMOW values that were nearly identical to that recorded for 'natural' 1. As to both 1 and 2, variations of synthesis conditions led to distinct changes in the delta(13)C(V)-PDB but not the delta(2)H(V)-SMOW values. Synthetic 3 showed delta(13)C(V)-PDB and delta(2)H(V)-SMOW values of -24.5 and -184 per thousand, respectively. These data differed from those found in raspberry fruit under study (n = 8), that is, ranging from -33.6 to -36.6 per thousand for delta(13)C(V)-PDB and from -200 to -225 per thousand for delta(2)H(V)-SMOW. The values determined additionally for 1 and 2 in raspberry fruit samples ranged from -30.3 to -35.1 per thousand and from -176 to -221 per thousand for delta(13)C(V)-PDB and delta(2)H(V)-SMOW, respectively, and thus corresponded to the already known literature information.     

Photodegradation of rotenone in soils under environmental conditions

An environmental fate study was performed to analyze the effects of soil components on the photochemical behavior of rotenone. Photodegradation experiments were carried out on three types of soil collected in southern Italy, Valenzano (VAL), Turi (TUR), and Conversano (CON), from April to June 2006. Soil thin-layer plates (1 mm thick) were spiked with 1.5 mg/kg of rotenone and exposed under natural conditions of sunlight and temperature. The plates were removed from the sunlight at predetermined intervals of continuous irradiation. Other soil samples, control and sterilized, were kept in the dark to evaluate possible effects of chemical and microbiological degradation during the irradiation experiment. The time for 50% loss of the initially applied rotenone varied from 5 to 7 h, following the order TUR < CON < VAL. In environmental studies, changes in temperature and/or moisture affected the degradation rate and caused deviations from first-order kinetics. The photolysis reaction fit the two compartment or the multiple compartment model pathways better. A fast initial decrease during the first 5 h of rotenone irradiation was followed by a much slower decline, which clearly indicates the rather complex chemical process of rotenone photodegradation on soil surfaces. Also, the degradation was shown to be directly related to the soil concentration of clay and organic matter. Rotenolone (12abeta-hydroxyrotenone) was detected by HPLC/DAD/MS analysis as the only photodegradation byproduct of rotenone in soil thin layers. Results provide additional insights on the rates and the mechanisms of rotenone degradation, aiming to describe more clearly the degradation performance of chemical residues in the environment.